This invention relates to a fluid processing apparatus and, more particularly, to an apparatus for use with chemical synthesizers.
It is often necessary in the biotechnology field to use support particles on which various biochemical reactions may take place. These particles may be various resins and typically may be polystyrene beads having a diameter in the range of 50-100 microns. Thus in the case of the synthesis of peptides, various amino acids must be linked together. When the amino acid chain contains 100 or more amino acids, it is called a protein. The chemical bond between two amino acids is an amide bond and is formed by the amine group from one amino acid combining with the carboxylic group of the next.
One of the synthesis techniques is to use a solid phase peptide synthesizer to add amino acid sequentially onto to an insoluble resin such as the polystyrene beads mentioned above. Synthesis begins with the attachment of the carboxylic end of an amino acid to the resin, and continues with one amino acid after another until the amino terminus of the desired peptide is reached. Various commercial resins are available for this purpose. The processing is usually accomplished in a non-disposable cartridge in which the various solvents and reagents necessary to the peptide synthesis are added to the cartridge, containing the beads, for each step of the synthesis process. After the reaction of each reagent is complete the reagent must be removed from the bead-containing cartridge, the beads washed, a new reagent added, etc. until the peptide synthesis process is complete. To speed the process it is preferable to remove the fluid reagents, solvents, etc. by applying a vacuum to the lower end of the cartridge.
The application of vacuum is similar to the techniques used in separating techniques using stationery beads using chromatographic techniques. Among such vacuum separators of the prior art is that described by Quame in U.S. Pat. No. 3,567,029. Quame describes the use of a disposable separating column filled with a particular solid phase, capable of extracting certain lipophilic compounds, including the most commonly encountered, abused drugs, such as phenobarbital, amphetamine, methadone and the like. In a typical drug extraction, such as from a urine sample, Quame allows the urine sample to pass through the column. The column selectively adsorbs any lipophilic drugs contained in the urine, thereby extracting the lipophilic drugs contained in the urine. Next, the adsorbed drugs are eluted from the column by a solvent and any residual aqueous phase is retained by a filter.
Another separating cartridge of this type is described by Forsythe, Jr., et al. in U.S. Pat. No. 4,214,993 which describes a three-piece cartridge including a cap, an extraction housing, a separating column, and a primary recovery cup. A secondary recovery cup may also be nested onto the lower end of the waste cup. The primary recovery cup has interior flanges for positioning and protecting the bottom end of the column against damage. Each of the elements has an enlarged upper portion forming an exterior step which facilitates mounting in the swinging bucket of a centrifuge. The column itself may comprise particles of a suitable separatory material with the top and the bottom of the particles retained by porous supports.
The Howell patent, U.S. Pat. No. 4,380,257, describes the use of a vacuum to increase the speed with which a fluid is withdrawn from the column. Another vacuum cartridge separation technique is described in an article entitled Automated On-Stream Syringeless Injection in HPLC, Kenneth C. Van Horne and Thomas Good, American Laboratory, October 1983.
These cartridges of the prior art do not meet all the needs of some of the biotechnology processing required particularly in the case of peptide synthesis. In this latter application, it is necessary (a) to mechanically agitate the cartridge to incur mixing; and (b) to facilitate the opening and the closing of the cartridge. Only when it is desired to regulate the application of the vacuum to remove the reagent need the cartridge be open. No provision is made in these prior cartridges to close the lower end other than by the use of an end cap. This is not convenient for use in synthesis operations where the cartridge must be opened and closed many times. It is necessary that the cartridge be closed during mixing of the reagents to prevent the leakage of fluid from the cartridge during the agitation period.